Chamomile is classified as toxic to dogs by the ASPCA. The plant, known scientifically as Anthemis nobilis (Roman chamomile), contains compounds that can cause gastrointestinal upset and other symptoms if a dog eats it. That said, the severity depends heavily on how much your dog consumed and in what form.
What Makes Chamomile Harmful to Dogs
Chamomile plants contain several naturally occurring irritants, including volatile oils and compounds related to coumarins, which are blood-thinning substances. When a dog chews on the plant itself or ingests a concentrated form like essential oil, these compounds can irritate the digestive tract and, in larger amounts, affect blood clotting.
The ASPCA lists chamomile as toxic to dogs, cats, and horses. The listing specifically covers Roman chamomile (Anthemis nobilis), which goes by many common names: manzanilla, garden chamomile, true chamomile, corn feverfew, barnyard daisy, ground-apple, and turkey-weed. German chamomile (Matricaria chamomilla) is a different species but contains similar active compounds, including the same coumarin-related substances that raise concern.
Symptoms to Watch For
A dog that has eaten chamomile may show signs of gastrointestinal distress: vomiting, diarrhea, drooling, or loss of appetite. These are the most common reactions and typically appear within a few hours of ingestion. In most cases involving a small amount of plant material or a lick of tea, symptoms stay mild.
Larger amounts or more concentrated forms (like essential oils) can cause more serious problems. Because chamomile contains coumarin-like compounds, heavy ingestion raises the risk of bleeding issues. Contact dermatitis, an irritation of the skin around the mouth and face, is also possible if a dog has been chewing directly on the plant.
Chamomile Tea vs. the Plant vs. Essential Oil
Not all chamomile exposure carries the same risk. A dog that laps up a small amount of cooled, diluted chamomile tea is in a very different situation than one that ate a handful of chamomile plants from the garden or got into a bottle of essential oil.
Chamomile tea is heavily diluted. A few sips are unlikely to cause anything beyond mild stomach upset in most dogs, and some veterinarians actually recommend very small amounts of chamomile tea for calming or mild digestive support. The plant itself is more concentrated and more likely to cause irritation if a dog eats a significant quantity. Essential oils are the highest-risk form because they pack the plant’s active compounds into an extremely concentrated liquid. Even small volumes of essential oil can overwhelm a dog’s system, particularly in smaller breeds.
The Blood-Thinning Risk
One concern that often gets overlooked is chamomile’s potential to interfere with blood clotting. The coumarin compounds in chamomile can theoretically amplify the effects of blood-thinning medications. A case documented in the Canadian Medical Association Journal described a patient on warfarin (a common blood thinner) who developed serious internal bleeding after using chamomile products. The researchers concluded that chamomile’s coumarin content likely worked in synergy with the medication.
This matters for dogs too. If your dog takes any medication that affects blood clotting, or if your dog is scheduled for surgery, chamomile exposure becomes a more serious concern. The blood-thinning effect of chamomile on its own is mild, but combined with other factors, it can become clinically significant.
What to Do If Your Dog Ate Chamomile
If your dog nibbled on a chamomile plant or drank some chamomile tea, note how much they consumed and watch for vomiting, diarrhea, or unusual lethargy over the next several hours. For small amounts, symptoms are usually self-limiting and resolve on their own.
If your dog ingested chamomile essential oil, ate a large quantity of the plant, or is showing symptoms that seem to be worsening, contact your veterinarian or the ASPCA Animal Poison Control Center (888-426-4435). Be ready to tell them your dog’s weight, what form of chamomile was involved, and roughly how much was consumed. Smaller dogs are at higher risk simply because it takes less of any toxic substance to affect them.
Dogs that are pregnant, very young, or already on medications deserve extra caution. Even amounts that might be harmless for a healthy adult dog could cause problems in these cases.
Keeping Chamomile Away From Your Dog
If you grow chamomile in your garden, consider fencing it off or planting it in raised beds your dog can’t easily reach. Store chamomile tea bags, loose-leaf chamomile, and especially essential oils in closed cabinets. Dogs are often attracted to the apple-like scent of chamomile (the name literally comes from the Greek for “ground apple”), so leaving it accessible on counters or tables is an invitation for curious noses.
For anyone using chamomile-based products around the house, like lotions, sprays, or diffusers, keep in mind that dogs can absorb compounds through their skin and by licking treated surfaces. Essential oil diffusers release particles into the air that settle on fur and paws, which your dog will eventually ingest through grooming.